van amstel



Aug. 11, 1959 J. J. A. P. VAN AMSTEL 2,399,610

ELECTRODE SYSTEM COMPRISING CRYSTAL DIODES OR TRANSISTORS Filed Oct. 20, 1954 I i 2 Sheet-Sheet 1 INVENTORS OHAN ES JACOBUS ASUE LOOSNIAN AMSTEL RUS Aug. 11, 1959 J. J. A. PQVANfAMSTEL 2,899,610

ELECTRODE SYSTEM COMPRISING CRYSTAL DIODES OR TRANSISTORS Filed Oct. 20, 1954 2 Sheets-Sheet 2 PLOOS VAN AMSTE AGENT V ELECTRODE SYSTEM..ClVlPRISING CRYSTAL DIODES'OR TRANSISTORS Johannes JacobusAsnerus Ploosvan Amstel, Eindhoven,

Netherlands, assignor, by mesne assignments-,to'North' American- PhilipsCompany, Inc., New York, N.Y., a corporation of Delaware This invention relates to electrode systems, for example crystal diodes or transistors, comprising a semi-conductive body constituted by at least two parts of diiferent or'opposite conductivity types. Said body. may be, for

example,- a mono-crystal manufactured by. so-called growing from a molten mass, it being possible to obtain layersofdifferent conductivity types by the addition of donors or acceptors to the molten mass of a semi-conductive material, on the surface of whichbody at one or more :areas electrodes areprovidedv by fusion, which are of a material suchasto yield parts of different or opposite -conductivity types due to alloyingwith'the constitutive material: of the body.

The object of the invention is-inter alia to improve the dissipation of heat from sucha system and thus to permit a higher electrical load.

It is common practice in such systems to securethe semi-conductive body to a carrier and to connect flexible conductors to the other parts,'thus preventing the occurrence of mechanical stress-in the semi-conductive body, which commonly comprises a very-brittle :crystalof ger-' manium or silicon.

The invention underlies the recognition that the dissipation of heat by such flexible conductors is unsatisfactory and that it is possible for not only one, but at least two parts ofzthe body to be connected directly, that is to say. withoutthe intermediary of flexible, conductors, to coolingbodies without detracting from the reliability of the. system.: I

According -touthe invention, atleasttwo partsof the semi-conductive body are each connected directly to a cooling body, thecooling bodies furthermore being rigidly interconnected by one or more insulating bridges. The term rigid connection is to be understood in thiscase to mean a connection which is mechanically much stronger than that brought about by the semi-conductive body.

The-cooling bodies may have the shape of plates which extend in parallel with one another through part of their surfaces, it being possible for the semi-conductive body, togetherwith one or more insulating bridges, to be provided between the parallel parts. The semi-conductive body is preferably so positioned that the boundaries between the parts of different conductivity type extend as far as possible in parallel with the said parts of the plates.

In manycases it may be advantageous to fOldiIhGiCODL ing plates in part, in order to improve the thermalccontact'with the surroundings.

In. order that the invention maybe readily carried into efiect, itwill now be described with reference to the accompanying drawing, given by way of example, in which:

Fig. 1 is a side view of a crystal diode arranged between two parallel cooling plates.

Fig. 2 is a perspective view of a variant of the construction shown in Fig. 1.

Fig. 3 is a perspective view of a third embodiment of a crystal diode.

2,899,619 Patented Aug. 7,11, 1,959

Fig. 4 is'a plan 'view 'ofthe saiddiode on an enlarged scale.

Fig.5 is ,a perspective view of. a transistor comprising.

cooling plates.

Fig. '6 is asectional view of the transistor of Fig. 5.

Figs.- 7 and 8 are a side view and a perspective view re-' spectively of two transistors.

Fig. 9 is a sectional viewof-one'embodiment of a crys tal diode:

Figs. 10 to 12 are sectional views of the .semi-conduc tive body With-adjoining parts onan enlarged scale;

The crystai'diode shown in Fig. 1 comprises two me tallic cooling plates 1 and 2, for example of brass, which are rigidly interconnected by insulating bridges 3 and 4. Said bridges may each comprise an insulating body, for example a, ceramic disc, which is connected to the plates with'the'use of a thermosetting cement. The plates-are separated 'by the semi-conductive body 5 .withan electrode 6 provided thereon by fusion. The body may consist of'germanium'of the N-type andthe electrode may consist of indium. The body 5 hassoldered-to its lower side a metallic plate 7 having a coeificient of expansion.

similarto that of germanium,'which plate serves to prevent the semi-conductive body from cracking as a result of its different coefiicient of expansion with respect to that of copper." The plate may consist of an alloy containing 54% of iron, 29% of nickel and 17% of cobalt, which alloy is known under the name Femico.

The assembly is secured between the plates 1 and 2.

with the use of a low-melting solder such as Woods metal The securing operation is preferably ,eife'cted by first providing each plate with a thin layer of Woods metal 8 and subsequently pushing the body 5,"together withthe-electrode 6 and the plate 7,between the plates 1 and 2,"the-Woods metal atthe same time-being fused by means of hot air.

It has been-found that at normal temperatures the rhechanicalstress in the body 5 'and the electrode 6 has no harmful consequences.

The supply of current is to be effected in this case through the plates 1 and 2.'

Fig. 2 shows a similar diode, but in which the plates '1 and 2 are interconnected with the use of flanged sleeves 9 and several insulating discs 10.

It will be evident that the body,5 and 'theelectrode may be protected from the action of the atmosphere. 'sur-t rounding thernbycastingwith. a sealing mass. Ethoxyline resins, also known underthe mark Araldit, are very suitable for. this purpose.

The. construction shown in Fig. 3, a plan view of which,

isshown again in Fig. .4 on-an-enlargedscale, substantially corresponds to that of Fig. l,'except--theplates- 1 and 2 are bentrectangularly along their edges so as to' facilitate the securing thereof on a base plate.

Figs. 5 and 6-show a transistor'comprising' three plates 11, 12 and 13 which arebent along their edgesand'rigidly secured to one-anothen Insulating discs 14 and -15 are shown between the plates 11 and. 12 as an example of securing and fixed imposition between the plates by cementing.-- Ceramic bodies ltd-shown between the'plates 11- and 13 may likewise be fixed in position by cementing; The

transistor :propercompnises -ia :semicondu'ctive body 17 having two electrodes 18 ;and:=19. The body-'17 further 3 time being fused by means of hot air. Afterwards, the body is cast in a protective mass 24.

The transistor shown in Fig. 7, as the diode shown 1n Fig. 1, is built up with the use of two cooling plates 1 and 2 which are rigidly interconnected along their edges at 3. However, the semi-conductive body 17, instead of being secured between the plates 1 and 2, is in this case secured to the edge of plate 1 through the intermediary of the Fernico plate 31. The electrode 18 is soldered to the plate 1 with the use of Woods metal 21, whereas the electrode 19 is connected through a conductor 32 to a contact 33 which is secured to an insulator 34 carried by the plate 2.

The transistor shown in Fig. 8 is distinguished from the preceding ones in that the semi-conductive body 17 is soldered in an aperture of the plate 1. The dissipation of heat may thus be more favourable.

The transistors shown in Figs. 7 and 8 aiford the advantage that the capacity between the electrode 19 and the conductors connected therewith may be low with respect to that of the other parts.

It will be evident that in these transistors and also in the diodes shown in Figs. 3, 4 and 7 the semi-conductive body may be cast in a sealing mass.

Finally, Fig. 9 again shows a diode. In this diode the semi-conductive body is constituted by a small ball 41 which may consist of, for example, germanium of the N-type. On one side thereof a thin layer 42 of a metal such as indium is provided by fusion, which layer brings about a p-n transition, whereas on the other side a sol dered joint 43 provided therein yields an ohmic contact, for example of tin. The plates 1 and 2 may exhibit apertures 44, which can accommodate the ball and the solder.

Heating to a temperature of about 500 C. is commonly required for manufacturing the p-n transition. This thermal treatment may be carried out before the ball is secured between the plates, in which event the insulating bridges 3 and 4 need not be resistant to high temperatures. It is alternatively possible to carry out the thermal treatment after the ball has been provided and in this casethe insulating bridges must be capable of withstanding a high temperature. They may then be manufactured, for example, from ceramic material, glass or similar material.

As previously mentioned, it is preferable that the semiconductive bodies should be so arranged that the boundaries between the parts of different conductivity types are as far as possible parallel to the cooling plates. This is shown in detail in Figs. 10 to 12, which illustrate several emllaodiments of the semi-conductive body on an enlarged sca e.

In the transistor shown in Fig. 10, the semi-conductive body 17 comprises two electrodes 18 and 19 which are provided in opposition by fusion. If the body consists of germanium of the N-type, the electrodes may be of indium. After the assembly has been subjected to a thermal treatment, for example at 500 C., the indium has alloyed with the germanium so strongly that the electrodes have penetrated the surface of the latter. After freezing, at least those parts of the electrodes 18, 19 which adjoin the material of the original body comprise a semi-conductor of the P-type. In order that the mechanical stress may be distributed through the body 17 as favourably as possible, it is desirable that the boundaries 51 and 52 between the parts 17, 19 should be parallel to the cooling plates 11 and 12.

Fig. 11 shows a transistor of the grown junction type. The semi-conductive monocrystal 61 comprises three parts 62, 63, 64 of opposite conductivity type, viz. of

4 the p-n-p or the n-p-n type. The crystal is connected with the use of solder 65 to two Fernico plates 66 which, in turn, are secured with the use of Woods metal 67 to the cooling plates 11 and 12. As before, the boundaries between the parts 62, 63, 64 are parallel to the said plates.

The diode shown in Fig. 12 is substantially similar to that shown in Fig. 9, except the parts 42 and 43, which may be of indium and tin respectively, are secured to the cooling plates 1 and 2 with the use of a low-melting metal 8. The boundaries 71 and 72 between the parts 41, 42 and 41, 43 are as far as possible parallel to the cooling plates 1 and 2.

If in cases as shown in Figs. 10 and 12 the said boundaries are curved, more or less, this implies that the axis of symmetry X-X of the semi-conductive body is at right angles to the adjoining parts of the cooling plates.

What is claimed is:

l. A semi-conductor device comprising a pair of cooling plates having parallel, spaced portions, a semi-conductive body containing at least two portions of opposite conductivity type material and secured directly to and between said parallel portions of said cooling plates with one conductivity type portion secured to one of said plates and with the other conductivity type portion secured to the other of said plates and with the opposite-conductivitytype portions extending substantially parallel to the parallel spaced portions of the cooling plates, and insulating supporting means secured and bonded directly to and between said parallel portions of said cooling plates and rigidly interconnecting the latter together.

2. A semi-conductor device as set forth in claim 1 wherein the insulating supporting means includes a pair of insulating members disposed on opposite sides of the semi-conductive body.

3. A transistor device comprising first and second cooling plates having parallel, spaced portions, a semi-conductor body containing emitter, collector and base electrodes mounted between said parallel portions of the cooling plates, one of said electrodes being secured directly to one of the parallel portions, another of said electrodes being secured directly to the other of said parallel portions, insulating means disposed between the parallel portions and secured thereto and rigidly interconnecting them together, a third cooling plate connected to at least one of the other cooling plates, and means connecting the third of said electrodes to said third cooling plate.

4. A transistor device comprising first and second cooling plates having parallel, spaced portions, a semi-conductor body secured edgewise to the edge of said first cooling plate, rectifying connections on opposite surfaces of said semi-conductor body, one of said rectifying connections being secured directly to said second cooling plate, insulating means secured to and between said parallel portions of said cooling plates and rigidly linking them together, terminal means insulatingly mounted on said second terminal plate, and means interconnecting said cooling means and the other of said rectifying connections.

References Cited in the file of this patent UNITED STATES PATENTS 2,414,801 Clarke Jan. 28, 1947 2,665,399 Lingel Ian. 5, 1954 2,703,855 Koch et a1. Mar. 8, 1955 2,745,044 Lingel May 8, 1956 2,754,455 Pankove July 10, 1956 2,759,133 Mueller Aug. 14, 1956 M .4 a FR-d 

